High power demountable tube



Oct. 30, 1934. L. A. GEBHARD HIGH POWER DEMOUNTABLE TUBE Filed March 14,1933 2 Sheets-Sheet 1 6 INVENTOR. QOM/io 61 mfilaw,

ATTORNEY Oct. 30, 1934. L. A. GEBHARD HIGH POWER DEMOUNTABLE 'lUBE FiledMarbh 14, 1933 2 Sheets-Sheet 2 INVENTOR. QmM/J 6L Bdfmd,

ATTORNEY I I I I. I. l w

Patented Oct. 30, 1934 "UNITED STATES PATENT OFFICE (Granted under theact of March 3, 1883, as

amended April 30, 1928; 370 0. G. 757) My invention relates broadly tohigh power electron tubes and more particularly to a sym metricalconstruction of demountable electron tube.

One of the objects of my inventionis to provide a construction of highpower demountable electron tube suitable for operation in pushpullsymmetrical amplification circuits.

Another object of my invention is to provide a construction of highpower demountable electron tube wherein the anode and control gridelements of two electron tube systems may be assembled in a demountablemanner in compact relation, the anodes forming envelopes for the tubewhich may be continuously exhausted for maintaining that degree ofvacuum required for operation of the electron tube systems.

Still another object of my invention is to provide a construction ofdouble electron tube'suitable for operation in push-pull symmetricalcircuits in which anode and control grid electrodes are concentricallymounted with removable insulation means for maintaining the electrodes.in position in cooperative relation to a replaceable cathode elementsupported between removable end members assembled with relation to theother elementso-f the tube electrodes.

A further object of my invention is to provide a construction of highpower double electron tube having fluid cooled anodes which areassembled in concentric relation with respect to control grids and areplaceable cathode element, the anodes forming, with insulation membersand end plates, a closedvessel subject to evacuation for maintainingthat degreeof vacuum within the vessel required for proper functioningof the electron tube. i 7

Other and further objects of my invention reside in the construction andassembly of coacting parts for a double electron tube as set forth morefully in the specification hereinafter following by reference to theaccompanying drawings, in which;

Figure 1 is a side elevation of a double electron tube with the anodesbroken away and illustrated in cross-sectionand showing the controlgrids and cathode in side elevation; Fig. 2 is a vertical sectional viewtaken through the double electron tube of my invention; Fig. 3 is a planview of the double electron tube of my invention; Fig. 4 is a transversesectional view taken on line 44 of Fig. 2; Fig. 5 is a transversesectional view taken on line 5-5 of Fig. 2; Fig. 6 is a fragmentary viewillustrating the two aligned control grids and the insulated bushingwhich is disposed therebetween; Figs. 7, 8 and 9 illustrate modifiedforms of packings which may be employed for effecting a tight seal forthe electron tube of my invention; and Fig. 10 shows a modified form ofretaining means employed for maintaining the end plates in alignmentwith the insulation members forming part of the double electron tube ofmy invention.

The double electron tubeof my invention has been developed with aview ofmeeting economic requirements in high power electron tube transmitters.The discarding of a high power tube structure, after a relatively shortterm of life, results in great expense. The attempt at renew ing thecathode in the ordinary type of high power tube introduces manydifliculties-and often produces economic waste. Thetube of my inventioncomprises parts which are readily assembled in demountable arrangementpermitting the replacement of defective parts, particu larly a burnedout cathode. The structure of my invention provides for the compactassembly of separate tube systems, each of which include a fluid cooledanode in coacting relation with a concentrically mounted controlgridanda replaceable cathode. The anodes and control grids are eachspaced by insulation members. 1 Insulation members are provided on theends of the anodes against which end plates are assembled and means areprovided for maintaining the end plates in position aligned'with theinsulation members on the ends of the anodes. Various types of jointsare provided for preventing the seepage of air into the chamber'formedby the anodes. The chamber is evacuated at such times as is necessaryfor maintaining the required vacuum within the electron tube. I providespecial means for centering the control grids with respect to theanodes. A special contact arrange-' ment is provided for establishingconnection between one of the control grids and the associatedcontrol'grid terminal carried by one of the end plates. In the event ofdeterioration of r electron tube. Mountings 4 and 4 are supported by theend plates 5 and 5' of the tube. The filament terminals are shown at 6and 6 connected to the end plates. The filament is positioned axiallythrough the tube. One filament suffices for the two halves of the tube.In a push-pull circuit, the radio frequency current between anode andgrid to the filament which normally has to pass through by-passcondensers is, in this arrangement, carried between the two halves ofthe filament. The only radio frequency current that the filamentterminals are required to carry is the unbalanced component in theneutral lead. Another advantage of the arrangement of the filament isthat there is a very short electrical path between the two halves of thetube. In the ordinary push-pull circuit using separate tubes, there isquite a length of lead through the bypass condensers from filament tofilament, where it is necessary to introduce plate meters for each tubein negative return lead.

The grids 2 and 2 are supported from end plates 5 and 5 in a mannersimilar to the disclosure in my application Serial No. 660,707 filedMarch 14, 1933, entitled Demountable electron tube. The grids areinsulated from each other by centrally arranged insulator bushing 7which also serves to align the grid structures with respect to the otherparts of the tube. The bushing 7 and other insulated parts of the tubeare constructed from suitable insulating material such as magnesiumsilicate or magnesium and aluminum silicates. The control grid terminalsare shown at 2a and 2a and are insulated by suitable bushing membersfrom end plates 5 and 5'.

The anodes are each arranged for liquid cooling. Tubular members 8 and8' form jackets 9 and 9' through which cooling liquid is passed. Theinlets 10 and 10' are adjacent to the joints between the anodes andinsulators 11, 11 and 12 which support them. This arrangement, togetherwith resilient gaskets 14 and 14' insures the tightness of the joints.

It will be appreciated that various forms of joints may be provided toprevent leakage of air into the chamber within the tube as illustratedfor example in Figs. '7, 8 and 9.

Throughout the several assembly views of the tube of my invention, Ihave illustrated gaskets at each of the joints which are placed undercompression for preventing the leakage of gas. To simplify theillustration of the invention, these gaskets have been illustratedschematically in the assembly views. However; I desire that it beunderstood that in practice the joints are formed with coacting facesestablishing a serpentine course through the joint which substantiallyprevents undesirable leakage and provides a gas tight seal. Fig. '7shows end plate 5 provided with an annular projection 5a which fits intoa coacting annular recess 11a in the insulator 11. The gasket 14 whichis disposed therebetween provides a substantial seal against the leakagei The insulator 11 is provided with a coacting face which is offset insteps or echelon formation as represented at lid. The gasket 14,disposed between the echelon faces 5d and 11d, serves to prevent seepageof gas between the joints. As I have pointed out, any one of the typesof joint illustrated, or any other form of joint may be used forinsuring a gas tight closure within the anode structure.

It will also be understood that the tension members 15 have beenillustrated schematically for the purpose of simplifying theillustration and that in practice I employ any suitable arrangement oftension adjusting means for compressing the end plates 5 and 5 againstthe gaskets 14, gaskets l4, insulator l1 and insulator 11, and againstthe anodes 8 and 8. One form of tension adjusting means has beenillustrated in Fig. 10.

Rod 20 of insulation material extends through the heads 5 and 5'provided with means thereon for drawing the heads together overinsulators 11, 12, and 11 with respect to anodes 8 and 8. The insulatedrod 20 has a metallic head 21 riveted thereon at one end to engage endplate 5. At the other end of the insulated rod 20, there is a sleeve 22riveted thereto and externally screw threaded to receive a thumb screw23 which is screwed against the top of the end plate 5. The tensionmember is preferably of insulation material to avoid capacity effectsbetween the anode structures and between the cathode and the anode. Inlieu of the tie rod construction, I may employ various forms ofturnbuckle constructions or other arrangements of tension members. Theoutlets 13 and 13 are located centrally with respect to the ends of eachof the anodes. As shown in Fig. 1, the parts of the tube are maintainedin assembled relation by longitudinal tension insulators 15 and nuts 16.Anode terminals are shown at 1'7 and 17. A connection for the exhaustpump is shown at 18.

The center part of the grid structure is shown more clearly and in morecomplete detail in Fig. 6. The grid support rings 19 and 19 slip overshoulders on the insulating member '7 which insures alignment of thegrid structure. The insulating member 7 is telescopically disposedcentrally within rings 19 and 19' carried by the supports for the grids2 and 2 for providing a rigid structure. Despite the rigidity of thestructure, the control grids may be readily d'sassembled or assembled.This structure of the bushing 7 allows ready assembly of the tube inthat the grids may be permanently fastened to their respective endplates and then inserted in the tube with insulated bushing 7 betweenthem.

When the tube is assembled, the control grids 2 and 2' are centeredconcentrically with respect to anode 8 and anode 8' and, at the sametime that electrical connection is maintained to terminals 2a and 2a.The aperture 5c in the end of end plate 5 is sufficiently large topermit the proper securing of the cathode l in the socket which connectsto mounting 4 by means of a tool insertable through the aperture 5e.

By reason of the short electrical paths in the tube of my invention, itis possible to operate at a considerably higher frequency than ispossible with a separate pair of ordinary tubes. The connections as theycome from the tube lend themselves readily to symmetrical circuit designso essential for proper operation of a push-pull system.

I have described my invention in certain preferred embodiments but Idesire that my inven- 11,978,423 tion be considered entirely in theillustrative sense, asI am fully aware that :many modifications in thestructure of the tube of my invention may be made by those skilled intheart, and I intend no limitations upon my invention other than areimposed by the scope of the appended claims.

I The inventionherein described maybe manufactur'ed and used by or.- forthe Govermentof the United States of Amerioafor governmental purposeswithout the payment of any royalty thereon or therefor.

' What I claim 'as new and desire to secure by Letters Patent of theUnited States is as follows:

1. A demountableelectron tube comprising a bers for said control gridscarried by the respective end plates.

2. A high 'power'tube' comprising a pair of cylindrical anodes, aninsulating sleeve disposed intermediate said anodes, an insulatingsleeve disposed over the ends of said anodes, end plates extendinglaterally across said last mentioned insulating means for securing saidend plates under compression for providing a substantially closed"chamber defined by said insulatingsleeves and by said anodes,a-replaceable filament supported between said end plates, a control gridsupported by each ofsaid'end plates, and means for insulatinglyconnecting said control grids at the adjacent ends thereof. i

3. A high. power tube comprising a pair of cylindrical anodes, aninsulating sleeve disposed intermediate said anodes, an insulatingsleeve disposed over the ends of said anodes, end plates extendinglaterally across said last mentioned insulating means for securing saidend plates under compression for providing a substantially closedchamber defined by said insulating sleeves and by said anodes, areplaceable filament supported between said end plates, a control gridsupported by each of said end plates, an insulating bushingtelescopically engaging adjacent ends of said con- 1 trol grids forcentering said control grids concentrically Within said chamber inspaced relation with respect to said filament and said anodes.

4. A demountable electron tube comprising a pair of cylindrical anodes,said cylindrical anodes j each having a shoulder on opposite endsthereof,

1 tending laterally with respect to said last mentioned sleeves, meansinterconnecting said end plates for maintaining said end plates inposition with respect tosaid anodes and said sleeves for providing asubstantially closed chamber, means for supporting a replaceablefilament between said end plates axially of said electron tube, acylindrical control grid insulatingly supported from each of said endplates, and insulation means coupling the adjacent ends of said controlgrids and I maintaining said control grids in concentric respect to saidanodes.

lationwith respect to said filament and with re- 5. A demountableelectron tube comprising a pair of cylindrical anodes, said cylindricalanodes each having a shoulder on opposite ends thereof, an insulatingsleeve disposed between the shoulders on the ends of adjacentcylindrical anodes, an insulating sleeve engaging the'opposite ends ofeach of said cylindrical anodes, end plates extending laterallywithrespect to said last mentioned sleeves, means interconnecting saidend plates for maintaining said end plates in position with respect tosaid anodes and said sleeves for providing a substantially closedchamber, means for supporting a replaceable filament between said endplates axially of said electron tube, a cylindrical control gridinsulatingly supported frome'ach of said end plates, and a ring memberof insulating material extending concentrically within the insidediameters of each of said control grids for supporting said controlgrids in demountable'relation concentrically with respect to saidfilament and said anodes.

6. A demountable electron tube comprising a pair of cylindrical anodes,said cylindrical anodes each having a shoulder on opposite ends thereof,an insulating sleeve disposed between the shoulders onthe ends ofadjacent cylindrical an odes, an insulating sleeve engaging the oppositeends of each of said cylindrical anodes, end plates extending laterallywith respect to said last men tioned sleeves, means interconnecting saidend plates for ma ntaining said endplates in position with respect tosaid anodes and said sleeves for providing a substantially closedchamber, means forsupporting a replaceable filament between said endplates axially of said electron tube, a cylindricalcontrol gridinsulatingly supported from each of said end plates, a ring membercarried by the adjacent ends of each of said control grids i in spacedrelation one to the other, and an in sulating bushing having 'a centralshoulder and oppositely extending cylindrical portions fitting withinthe said ring members for insulatingly mounting said control grids inconcentrical relation with respect to said filament and said anodes.

'7. A demountable electron tube comprising a pair of cylindrical anodes,said cylindrical anodes each having a shoulder on opposite ends thereof,an insulating sleeve disposed between the shoulders on the ends ofadjacent cylindrical anodes,

an insulating sleeve engaging the opposite ends of each of saidcylindrical anodes, end plates extending laterally with respect to saidlast mentioned sleeves, means interconnecting said end plates formaintaining said end plates in position with respect to said anodes andsaid sleeves for providing a substantially closed chamber, means forsupporting a replaceable filament between said end plates axially ofsaid electron tube, a cylindrical frame insulatingly supported on eachof said end plates, an insulating member interconnecting saidcylindrical frames in a position intermediate the ends of said anodes, acontrol grid Wound upon each of said cylindrical frames, and e aterminal insulatingly mounted on each of said end plates and connectedwith the control grid supported thereon.

8. A demountable electron tube comprising a pair of cylindrical anodes,said cylindrical anodes each having a shoulder on opposite ends thereof,an insulating sleeve disposed between the shoulders on the ends ofadjacent cylindrical anodes, an insulating sleeve engaging the oppositeends of each of said cylindrical anodes, end plates extending laterallywith respect to said last mentioned sleeves, means interconnecting saidend plates for maintaining said end plates in position with respect tosaid anodes and said sleeves for providing a substantially closedchamber, means for supporting a replaceable filament between said endplates axially of said electron tube, a frame insulatingly mounted oneach of said end plates, means insulatingly connecting said frames in aposition intermediate said anodes, a control grid wound upon each ofsaid frames, a terminal insulatingly mounted on each of said end platesand connected with the control grid supported on the frame carried bythe said end plate.

9. A high power electron tube comprising a pair of tubular anodes, aninsulating sleeve disposed between said anodes, an insulating sleevecarried by the opposite ends of said anodes, end plates extendinglaterally across the ends of said last mentioned sleeves, means forsecuring said end plates, said insulating sleeves and said anodes inassembled relation for provid ng a closed chamber therebetween, areplaceable filament supported between said end plates, insulation meanscarried by the interior face of each of said end plates, a tubularcontrol grid supported by the insulation means on each of said endplates, said control grids projecting toward each other, and insulationmeans interconnecting said control grids and disposed about saidfilament for centering said control grids concentrically within saidchamber.

10. A high power electron tube comprising a pair of tubular anodes, aninsulating sleeve disposed between said anodes, an insulating sleevecarried by the opposite ends of said anodes, end plates extendinglaterally across the ends of said last mentioned sleeves, means forsecuring said end plates, said insulating sleeves and said anodes inassembled relation for providing a closed chamber therebetween, areplaceable filament supported between said end plates, insulation meanscarried by the interior face of each of said end plates, a tubularcontrol grid supported by the insulation means on each of said endplates, said control grids projecting toward each other, and a tubularinsulator disposed between the adjacent ends of said tubular controlgrids and in alignment with the insulating sleeve between said anodes.

11. A high power tube comprising a pair of fluid cooled tubular anodes,each of said anodes having a projecting sleeve thereon, an insulatingbushing enveloping the projecting sleeves on the adjacent ends of saidanodes, an insulating bushing on the opposite ends of said anodes, endplates extending laterally of said last mentioned insulating bushing,means for compressing said end plates, said insulating bushings, andsaid anodes in sealed relation for providing a substantially air tightclosure, a removable filament extending axially between said end plates,separable control grids carried by each of said end plates, and meansfor maintaining said control grids in concentric spaced relation withrespect to said filament and said anodes.

12. A ln'gh power tube comprising a pair of fluid cooled tubular anodes,each of said anodes having a projecting sleeve thereon, an insulatingbushing enveloping the projecting sleeves on the adjacent ends of saidanodes, an insulating bushing on the opposite ends of said anodes, endplates extending laterally of said last mentioned insulat- [05 ingbushing, means for compressing said end plates, said insulating bushingsand said anodes in sealed relation for providing a substantially airtight closure, a removable filament extending axially between said endplates, independent control grids insulatingly supporting each of saidend plates and projecting toward each other, and a tubular insulatorforming an annulus about said filament and engaging adjacent ends ofsaid control grids for maintaining said control grids in spaced relationconcentric with said filament and said anodes.

LOUIS A. GEBHARD.

